Ebhest bissois



ERNEST BISSON, `O

MARINERS PATENT Ormea.

F PARIS, FRANCE.

COM PASS.

SIECIFICATION forming part of Letters Patent No. 289,209, dated November 27, 1883. Application filed July 17, 1853. (No modul.)

To all whom/t may concerns Be itknown that I, ERNEsTBIssoN, of Paris, France, have invented certain new anduseful Improvements in `Mariners Compasses, intended more particularly for use on iron ves,-

sels; and I do hereby declare that the follow` alidade carrying one or more magnetic bars,

with provisions for changingy the alidade and its connections into various positions relatively to the needle, which is' inclosed within the circuit thus traversed. I employ two needles, one above and one below the trunnions.

In carrying the invention into practice, I provide a copper box containing two compasscards, each with an independent magnetic needle and mounted one over the other. The box has a glass top, and is made in two parts joined together by screws. The glass top is perforated in the center and provided with a barrel or bush, permitting a shaft to extend through the top and allow its being turned, as required, by a button on the'outer end. llhe shaft carries an internal alidade, on which are mounted two bar-magnets. The fixed bush in the center of the top is also fitted to form a bearing for an externalalidade. (Not shown.) The whole is suspended in an ordinary gimbal` ring by means of trunnions, as usual. The two magnetic needles are carried on screwpivots tapped through cross-bars in a central supporting-frame of copper. v The following is adescription of what I consider the best means of carrying out the invention.

The accompanying drawing forms a part of this specication and is a central vert-ical section. .A is a copper box, B, the cover; C, the plate-glass in the cover; C', a iixed bushing or needles; E', a crossbar thereof. isthe in- It carries two bars, N S, N`

ternal alidade.

S', of magnet-ized steel. This may be turned,

as required, injvarious directions by turning` the shaft G', which extends up through .the

The lower pivot, J', is tapped through the bot'- tom of the box.

M M is the upper magnetic needle, delicately mounted on the pivot J in the ordinary manner. It carries a compass-card, K.

M M is the lower magnetic needle. It is of the same length as the upper needle, M, but considerably heavier. It is mounted on the lower pivot, J and carries a compass-card, K. The height of either or both these needles may be 4regulated by turning the corresponding screw-pivots, J and J.

R is a horse-hair. stretched up and down in the position represented.- It might, without The upper explanation, be understood from the drawing that the uprights of the frame E are in the same plane as the hair R. This is not the fact. It is so shown in the drawing only for convenience rlhe plane of the uprights E may be transverse to the plane of the drawing.

P is a column or post, sustaining, by means of a hinge, Q, two mirrors, O, flexibly connected together by a hinge, O. v

S2 is an adjusting-screw. By means of the hinges and this adjusting-screw the mirrors O O may be easily set so as to show to the observer both the compass-cards K and K the upper card, K, being reflected in the upper mirror, and the lower card, K', being reflected in the lower. These mirrors stand at a different angle and show the images close together. The trunnions by which the box is supported on the gimbal-ring D are low, but I cause the box and its contents to maintain their equilibrium byloading the base ofthe box with lead or other heavy weights. The magneticnee- 1 dles M M, being of different weights and arranged with their axes or pivots in the same vertical line, are iniluenced to different extents hub of metal in the center of the cover; E, a

by the earth-currents and by the magnet-bars on the alidade or alidades. In adjusting my IOC) compass on a anew. shaft or in a new position on the old one, the direction of both the nee-J dles is carefully noted, and if found to indicate wrongly the alidade G is turned by means of the button H and pin G until the iniiuence of the magnets N S-,andv N S counteracts the disturbing iniiuence of the iron of the vessel, or of anchors, cables, guns, or the like in the vicinity, and causes them to indicate correctly'. In case both cannot be correctly adjusted, the alidade is turned until one needle indicates correctly, and that needle' is depended upon for correct indications in all subsequent uses of the instrument. Thetwo needles, mounted one above the other, and of unequal weights, tend to correct each other. The alidade corrects both.

vention the two needles should be placed about ten or fifteen centimeters apart. I attach irn-lr portance to the fact that the needles are of equal length and of unequal weight; also, to the fact that the mirrors are hinged together 1 and capable of adjustment to allow both compasscards to be seen simultaneously; also, Vto the fact that the gimbal-ring is low and about equally distant from each ofthe two compass! cards; alsoto the fact that all the delicate parts are inclosed within atight box. Modifications maybe made in the forms and proportions.

For the best operation of my inv Itis not essential that the distance of the magnetic bars N S, N S from the two needles shall be exactly equal. I prefer the arrangement shown.

I claim as my invention- 1. In a compass for iron vessels, the alidade G, carrying short magnetic bars N S, N S, in combination with the shaft G', extending upward 'through the hub C', and with the turning means, II, mounted above the latter, all arranged relatively to eachother and to a compass-needle, M, as herein specified.

2. In a compass for iron vessels, the two mirrors O O, in combination with the two needles M M and the two cards K K, as herein specified.

3. In a compass for iron vessels, the gimbalring D, suspended box A B, having a loaded base, one or more alidades, G, with means for adjusting the same, and `two magnetic needles,

M M', combined and arranged to serve as herein specified.

In. testimony whereof I have signed this specification. in the presence of two subscrib-` f 

